The present study was designed to investigate the role of HLA-class I (A and B) and class II (DR and DQ) antigens and blood group phenotypes in the aetiology of inflammatory bowel disease (IBD) in a sample of Iraqi patients. The patients were also evaluated for total and differential counts of leucocytes, subpopulations of lymphocytes (CD3+, CD4+, CD8+ and CD19+ cells) and phagocytosis. Sixty–five patients with IBD were investigated during the period May-December, 2004. The disease was clinically diagnosed by the consultant medical staff at Al-kadhamyiah Teaching hospital and Gastrointestinal Tract (GIT) and liver disease Center in Baghdad. The diagnosis was based on a clinical evaluation using colonoscopy and a histopathological examination of a biopsy. According to the point view of consultants, the patients were clinically subdivided into ulcerative colitis (ULC; 50 patients) and Crohn’s disease (CRD; 15 patients). A control sample of 67 individuals (apparently healthy), matched for age, sex and ethnic background (Arab Muslims), were further investigated. At HLA-class I region, the total patients showed significant increased frequencies of A9 (52.3 vs. 17.9%) and B41 (66.1 vs. 5.9%), and a significant decreased frequency of A11 (3.1 vs. 22.4%) as compared to controls, and similar findings were outcome when the clinical types (ULC and CRD) were considered. While at HLA-class II region, DR8 was significantly increased in the total patients (30.8 vs. 8.9%), but neither ULC nor CRD maintained such association, and instead ULC was significantly associated with DQ1 (40 vs. 18%). However, comparing ULC with CRD revealed a significant difference in the antigen B16 (2 vs. 33.3%). Blood group phenotypes (A, B, AB and O) were similarly distributed in the patients (total and subtypes) and controls, and no significant difference was observed as judged by Chi-square analyses. However, summing A, B, and AB blood groups increased their frequency to 60% in CRD patients, while their frequency in the controls was 51.4%. The total count of leucocytes showed no significant differences between patients (total and subtypes) and controls, while the differential count showed some variations. The neurophil count was significantly increased in total patients and ULC patients, while monocytes and eosinophils showed significant decreased counts in the patients (total and subtypes). Lymphocytes positive for the markers CD3, CD4 and CD19 showed significant increased percentages in total, as well as, ULC patients, while CD8+ cells were significantly increased in the total and subtypes of IBD patients. However, the CD4/CD8 ratio was significantly decreased in the patients (total and subtypes). The phagocytic index of patients (total and subtypes) was significantly increased, while the NBT index showed a significant elevated percentage in the total IBD and ULC patients.
